I think you are absolutely right. I think we should be preparing for a future without fossil fuels, and efficiency should stimulate production of renewable energy.

Therefore many policies people are encouraging to limit energy use will raise the proportion of renewable energy( and possibly lower FF use, but not necessarily).

Necessarily not, in certain circumstances. It depends on the rate of decline of exergy availability and on the rate of exergy payback of the alternative exergy sources.

When the availability of exergy is declining, it would be a brave or tyrannical government that would deprive the rest of its economy of large amounts of it to make investments that will break even in exergy terms only after years.

3) "Energy efficiency does not limit production of fossil fuels; it raises prices stimulating production. Therefore many policies people are encouraging to limit global emissions will in fact raise global emissions.

Could be re-stated to take account of renewable energy as:

Energy efficiency does not limit production of energy; it raises prices stimulating the production of alternative non-FF sources. Therefore many policies people are encouraging to limit energy use will raise the proportion of renewable energy( and possibly lower FF use, but not necessarily). What do you think?

Both of you are making hidden assumptions.

For the author:

1. "Energy efficiency does not limit FF production; it raises prices, stimulating production."
2. Assumption: nothing else limits FF production or consumption.
3. "Therefore many policies people are encouraging to limit global emissions will in fact raise global emissions."

That unstated assumption is necessary for your conclusion, but is known to be false. The simplest example is one of the biggest: personal cars. For most of the industrialized world, fuel costs are only a small part of the cost of an incremental mile driven, with the cost in time usually being the dominant factor and vehicle wear often being the dominant economic factor. If vehicle efficiency doubled, Westerners would not suddenly want to drive twice as many miles.

Fundamentally, it's a mistake to ignore human behaviour when you're trying to model human behaviour.

Neil's response is much better this way, but is still making assumptions:

1. "Energy efficiency does not limit FF production; it raises prices"
2. Assumption: raising energy prices stimulates the production of alternative non-FF sources.
3. Assumption: price rises caused by efficiency will increase the proportion of renewable energy.
4. "Therefore many policies people are encouraging to limit energy use will raise the proportion of renewable energy"

As with Ian, these assumptions are necessary to your conclusion. These assumptions are much more reasonable - witness the massive surge in interest in renewable energy during the recent FF price rises - although still somewhat questionable (i.e., if the only change is an increase in efficiency, then the relative prices of a kWh of renewable and non-renewable energy will stay the same, which doesn't provide much reason to change their mix).

A much stronger impetus to change the energy mix is likely to come from external factors such as FF scarcity and internal factors such as carbon taxes, as both of these will tend to raise the price of FF energy much more than renewable energy. I expect both of these to have a large effect in the next 50 years.

A second likely factor is changing energy vectors. Electrified rail, for example, is not only 3x more efficient than diesel rail, it's also much more flexible, as it can accept fuel from many sources. A fuel switch from diesel to electricity, then, not only offers the potential for emissions reductions from increased efficiency (as it's improbable that goods transportation would triple due to lower fuel requirements), but also based on fuel type, as the electricity could be derived from lower-emission sources.